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91.
Identification and quantification of bisphenol A and bisphenol B in polyvinylchloride and polycarbonate medical devices by gas chromatography with mass spectrometry 下载免费PDF全文
Pascal Gimeno Coline Spinau Nelly Lassu Annie‐Franoise Maggio Charlotte Brenier Laurent Lempereur 《Journal of separation science》2015,38(21):3727-3734
A gas chromatography with mass spectrometry method has already been developed and published for the identification and quantification of 14 phthalates and five nonphthalate plasticizers in polyvinylchloride medical devices. In order to assay, in addition to plasticizers, bisphenols A and B possibly present in polyvinylchloride samples, this previous method was extended to the assay of these additional potential endocrine disruptors. Furthermore, as bisphenol A could also be present in polycarbonate samples, the method used for the polyvinylchloride sample was tested and validated for the assay of bisphenols A and B in polycarbonate medical devices. The separation of all compounds, including bisphenols A and B, is obtained on a cross‐linked 5%‐phenyl/95%‐dimethylpolysiloxane capillary column using a temperature gradient. For both plastics, samples are dissolved in tetrahydrofuran followed by a precipitation of the plastic by addition of ethanol. Results obtained point out residual bisphenol A amounts for polycarbonate samples ranging from 0.6 to 0.8% and for polyvinylchloride samples less or equal to 5 ppm. No bisphenol B was detected in the samples tested. For bisphenols A and B, mean recoveries obtained on spiked polyvinylchloride or polycarbonate sample preparations ranged from 87 to 108% in accordance with in‐house specification (80–110%). 相似文献
92.
Nelly Jorge N lida Peruchena L zaro Cafferata Eduardo A. Castro 《Journal of Molecular Structure》1994,309(3):315-324
We have made a conformational study of tetroxane and its bi- and tetra-halogenated derivatives by means of the semiempirical AM1 and PM3 molecular orbital methods. The results are compared with previous semiempirical and ab initio studies as well as with available experimental data. We have found that in every case the AM1 method underestimates the peroxidic O-O bond length by approximately 12%, while the PM3 procedure describes such a bond in a better way. The degree of accuracy of these two semiempirical methods is discussed in relation with the tetroxane structure. 相似文献
93.
(Accepted July 23, 1996) 相似文献
94.
The volatile components of the flowerheads of Centaurea eryngioides Lam. and Centaurea iberica Trev. var. hermonis Boiss. Lam. were obtained by hydrodistillation and identified by GC and GC-MS. Altogether 91 components, mostly fatty acids and hydrocarbons, were identified. 相似文献
95.
Julia E. Morozova Ella Kh. Kazakova Eduard Ph. Gubanov Nelly A. Makarova Victor P. Archipov Tatjana V. Timoshina Zaymil Sh. Idijatullin Wolf D. Habicher Alexander I. Konovalov 《Journal of inclusion phenomena and macrocyclic chemistry》2006,55(1-2):173-183
Present paper reports on tensiometric studies of tetramethylsulfonatoresorcinarenes 1 and 2 with nonionogenic guests 3 and 4, pyrimidin derivative and O,O-dymethyl-1,1-dimethyl-3-oxobutylphosphonate, respectively. Association of resorcinarenes with these guests leads to dramatic change of adsorption characteristics of their solutions. CCMs1 of associates (1&3, 1&4, 2&3, and 2&4) are lower and the estimated surface activity, as well as the height of adsorption layers are higher than for individual substances. Aggregation of compounds 1–4 and association of 1 with 3 and 4 in solution were confirmed by 1H NMR spectra and studied by diffusion NMR with impulse magnetic field gradient. 相似文献
96.
Bruno M Rosselli S Maggio A Piozzi F Scaglioni L Arnold NA Simmonds MS 《Chemical & pharmaceutical bulletin》2004,52(12):1497-1500
Two new neoclerodane diterpenoids, 6-deacetyl-teucrolivin A (5) and 8beta-hydroxy-teucrolivin B (6), were isolated from the aerial parts of Teucrium orientale, along with four already known neoclerodane diterpenoids, teucrolivin A (1), teucrolivin B (2), teucrolivin C (3) and teucrolivin H (4), previously isolated from Teucrium oliverianum. Their structures were elucidated on the basis of spectroscopic evidence and chemical transformations. Compounds 1-3 were assayed for antifeedant activity against Spodoptera littoralis, S. frugiperda and Heliocoverpa armigera. Teucrolivin A was the most potent of the three compounds tested. 相似文献
97.
Salives R Dupas G Plé N Quéguiner G Turck A George P Sevrin M Frost J Almario A Li A 《Journal of combinatorial chemistry》2005,7(3):414-420
The 3-chloropyridazine moiety was immobilized on a Wang resin, using two different methodologies. The first of these involved direct nucleophilic substitution of 3,6-dichloropyridazine with the alcoholate of Wang resin. The experimental conditions were optimized. The second method involved a Mitsunobu reaction between the Wang resin and 6-chloropyridazin-3-ol during which a problem of regioselectivity was observed. The so-obtained chloropyridazine-containing resins were subsequently reacted with various arylboronic acids under Suzuki conditions. Acid cleavage yielded 6-arylpyridazin-3(2H)-ones with high chemical purity. 相似文献
98.
[structure: see text] A novel cyclic peptide, callynormine A, was isolated from the Kenyan marine sponge Callyspongia abnormis and its structure elucidated by interpretation of its NMR data and X-ray diffraction analysis. Callynormine A represents a new class of heterodetic cyclic peptides (designated endiamino peptides) possessing an alpha-amido-beta-aminoacrylamide cyclization functionality. 相似文献
99.
Ella Kh. Kazakova Albina U. Ziganshina Liya A. Muslinkina Julija E. Morozova Nelly A. Makarova Asija R. Mustafina Wolf D. Habicher 《Journal of inclusion phenomena and macrocyclic chemistry》2002,43(1-2):65-69
The flexible bowl-type water-soluble molecule1, consisting of a resorcinol core and fourconvergent tetrasulfonatomethylene groups, existingas a tetraanion in neutral water solution, was studiedas the host molecule for recognition of-aminoacids. Out of 12 examined guestmolecules only those possessing aromatic hydrophobicmoieties or a long hydrophobic chain with a second ionogenic groupform inclusion complexes with 1. The complex formationwas considered with the help of both 1H NMRand pH-metric titration in a broad range of pH.The role of host and guest geometric complementarity aswell as additional – and hydrophobic interactionsis discussed. The lack of these interactions inaqueous media provides domination of the guestsolvation by water over the 1 : 1 complexformation with 1. 相似文献
100.
Andrieux D Jestin J Kervarec N Pichon R Privat M Olier R 《Langmuir : the ACS journal of surfaces and colloids》2004,20(24):10591-10598
Adsorption isotherms of 2,5-dimethylpyridine (2,5-DMP) on Aerosil 200 silica from water-2,5-DMP binary mixtures are known to exhibit special features indicative of surface phase transitions in the adsorbed layer. We have made similar observations on another substituted pyridine, 2,4,6-trimethylpyridine (2,4,6-TMP). By using 1D and 2D NMR spectroscopy, we investigated adsorbed layers on silica in suspension in water/substituted-pyridine mixtures and demonstrated the existence of adsorbed species specific signals. Comparison of signals with those displayed on NMR spectra of liquid binary mixtures under various pH conditions rules out adsorption via interaction of the surface silanol group and the lone electron pair of the nitrogen atom. A mechanism of adsorption through the interaction of surface siloxane oxygen and the aromatic pi-system is proposed; it is consistent with both thermodynamic measurements and stacking of substituted pyridines within the adsorbed layer. 相似文献